Boeing Stearman Model 75, part seven. The Stearman in America, part four. USAAC, USN and USAAF users

 

The Boeing Stearman Model 75 is an American biplane of which 10,626 exemplars were manufactured from 1934 until the mid 1940s. 
It served as a primary trainer for both the United States Army Air Forces (USAAF) and the United States Navy (USN) throughout World War 2. 

During late 1933 Mac Short, Harold W. Zipp and J. Jack Clark, engineers at Stearman Aircraft, took a Lloyd Stearman's design made back in 1931 and added cantilever landing gear and adjustable elevator trim tabs to come up with the Model 70, which was able to withstand +12g  and -9g forces. 
This initial Model 70 was powered by a single 210 hp Lycoming R-680 radial engine and flew for the first time on 1st January 1934, with additional test flights being performed later at Wright Field, Naval Air Station (NAS) Anacostia and NAS Pensacola. The performance pleased the USN and requested a similar model to be built under similar specifications, including a 200 hp Wright J-5 engine. This model was designated as NS-1 by the USN and 41 were ordered, with enough spares to build additional 20 machines.

In 1934 Stearman became a subsidiary of Boeing and therefore its aircraft were known as Boeing-Stearm. It was during the summer of that year when Stearman engineers improved the Model 73 (the internal denomination for the aforementioned NS-1) into the Model X75. This lead to the United States Army Air Corps (USAAC) to evaluate the plane that autumn. The Model X75 was powered either by a 225 hp Wright R-760 or a 225 hp Lycoming R-680. The USAAC accepted the model and ordered in July 1935 26 machines powered with the Lycoming engine, designated at PT-13A (PT stands for 'Primary Trainer') with the USN ordering twenty more. In August 1936 the USAAC ordered fifty PT-13As more with thirty more being ordered in October that same year and twenty-eight more in December. 

On 6th June 1941 the US Government approved the civilian version of the Model 75, designated as Model A75L3 (PT-13) and Model A75N1 (PT-17), with around 60 being sold to civilian flight schools such as Parks College of Engineering, Aviation and Technology, the export market and the many British Flying Training School Program across the USA.

This program was established at the beginning of World War 2, when the United Kingdom recognized the need to train a large number of pilots, so a large number of flying and aircrew training schools were set up across the British Empire and some neutral nations like the USA, where pilots could be trained without the risk of enemy interference. 

The British Flying Training Schools were also set up in the United States from 1941 onwards as a result of the Lend Lease Bill. Seven schools were opened (numbered from one to seven, two in Texas, two in Oklahoma and one in California, Arizona and Florida) and of those, at least five of them were equipped or had the PT-13A/PT-17 in their ranks at some point. 

On 15th March 1941 Boeing delivered its 1000th trainer to the USAAC and the 1001th trainer to the USN. Later, on 27th August 1941 the 2000th trainer was delivered to the USAAC. This feat was followed on 27th July 1944 when the company delivered the 10,000th primary trainer.

After World War 2, thousands of surplus PT-17s were sold to civilians and former military pilots. Many were modified as crop-dusters with a hopper for pesticide or fertilizer fitted in place of the front cockpit. Additional equipment included pumps, spray bars and nozzles placed below the lower wings. 

Sources:

1st https://en.wikipedia.org/wiki/Boeing-Stearman_Model_75

2nd https://en.wikipedia.org/wiki/British_Flying_Training_School_Program

Curtiss SBC Helldiver, part one. The Helldiver in the US Navy

 

A contract was signed in August 1936 by the US Navy for the delivery of 83 SBC-3 (Curtiss Model 77A - according to the internal denominations given by Curtiss). On 17th July 1937, their delivery process began, with the first aircraft being deployed with Scouting Squadron Five (VS-5) assigned, theoretically, on board of USS Yorktown (CV-5), however, as Yorktown was commissioned until 30th September 1937, they remained on land, while the ship underwent sea trials. It wasn't until 10th December that same year when the VS-5 was embarked on the Yorktown, where the Helldivers served until 1940 when they were replaced by the Douglas SBD-3 Dauntless. 

By June 1938 three of the five scouting squadrons assigned to aircraft carriers (USS Enterprise -CV-6, USS Yorktown - CV-5 and USS Saratoga - CV-3), were equipped with the Helldiver, while the other two were equipped with the Vought SBU-1. 

A single SBC-3 was kept by Curtiss and re-engined with a 750 hp Wright R-1820-22 nine cylinder radial engine. It received the denomination of XSBC-4, which served as the prototype for the SBC-4. 

An initial contract was signed for a batch of 58 SBC-4, on 5th January 1938, followed by two additional contracts, one for 31 Helldivers on 27th July 1938, and a third one for 35 more on 13th August 1938, making a total of 124 contracted aircraft, powered all of them by the Wright R-1820-24 radial engine, yielding 850 hp of power.

Scouting Squadron 2 (VS-2), on board of USS Lexington (CV-2) was the first one to receive the SBC-4 Helldiver, replacing their Vought SBU-1s. By 26th June 1939, VS-2 was completely equipped with 21 SBC-4s. The Lexington was the only carrier to actually fly the Helldiver, during military maneuvers, as they were replaced by Douglas SBD-2 and SBD-3 Dauntless dive bombers in 1941, prior to Pearl Harbour. 

Given the expanding aviation training programme, most of the SBC-4s, with other training aircraft, were assigned to Naval Reserve Air Bases (NRAB), to allow reserve US Navy and US Marine airmen assigned to reserve scouting squadrons, and maintain their proficiency. 

As time went by, the US Navy acquired more modern aircraft and both SBC-3 and SBC-4s were replaced by, mainly the Douglas SBD Dauntless. By 7th December 1941, both US Navy and US Marines, had a total of 69 SBC-3 and 118 SBC-4s, based at Naval Air Stations (NAS), NRABs and the Naval Aircraft Factory in Philadelphia, Pennsylvania. The largest group was based at NAS Miami, in Florida, where they were used for intermediate flying and dive bombing training.

The carrier USS Hornet (CV-8) was also equipped with SBC-4, at the time of Pearl Harbour. This carrier was undergoing sea trials on the Atlantic Ocean on 7th December and the two squadrons equipped with the Helldiver kept them until the ship sailed to San Diego, California, in March 1942. By that time, both squadrons had transitioned to the Dauntless, though their aircraft were not replaced yet, making the Hornet the last ship to operate the Helldiver aboard and aircraft carrier. 

The last SBC-4 Helldiver was built in May 1941 and, by 1944, the last SBC-3, was seriously obsolete and they were stricken off the inventory. The longest surviving one were a group of 12 aircraft, based at NAS Jacksonville, Florida, which were stricken on 31st October 1944.

Sources:

1. https://en.wikipedia.org/wiki/Curtiss_SBC_Helldiver

2. Signal Squadron - Aircraft In action 151 - SBC Helldiver in Action

3. https://www.valka.cz/Curtiss-SBC-Helldiver-t45473

Pics re-drawn from:

http://wings-aviation.ch/53-Military-Aircraft-in-Detail/Curtiss-Helldiver/Attack.htm

Grumman J2F Duck, part two

 

When the last production Grumman JF-3 rolled out the factory on 18th October 1935, Duck production was halted for a time until March 1936, when a completely new design was ordered.

Instead, Grumman decided to revise their G-20 design and, the result, called G-15 by the company, was given the designation of J2F by the US Navy. The J2F differed from the previous JF in many ways. It was powered by a 750 hp Wright R-1820-20 air-cooled radial engine with a short chord engine cowling. The float was extended forward by one foot (0.3048 meters), making the design longer than the regular JF Duck.

The J2F also was able of carrying more additional equipment to make the aircraft more multi-role, like target-towing, smoke-laying and photographic survey and reconnaissance, apart from medical evacuation as one stretcher could be fitted in the passenger compartment, in place of the usual two seats. It could also serve in the typical light-transport role. The airframe remained basically the same as the JF, with the exception of the longer float, and wings remained unchanged. 

The first J2F-1 flew on 3rd April 1936 and was delivered to NAS Anacostia, in Washington DC. It was equipped with fittings for a single 0.30 in machine gun, bomb racks on the lower wing, and a tailhook to operate from carriers. By 1937 a total of twenty-nine J2F1 were completed. 

The first J2F-1 was hold at Anacostia for testing purposes, one of which involved the installation of full span flaps on the trailing edges of the upper wing, to try and lower the landing speeds to 65 mph (104.607 km/h). This aircraft was unofficially known as the J2F-1A.

In 1938 Grumman was tasked with the manufacture of thirty J2F-2. This variant was powered by a 790 hp Wright R-1820-30 radial engine and was armed with a single forward-firing 0.30 in machine gun, plus a flexible one placed at the rear cockpit. This variant was mainly built of the Unites States Marine Corps.

During the next two years, nine J2F-2s were stationed at Charlotte Amalie, Saint Thomas, American Virgin Islands, as part of the neutrality patrols over the Caribbean Sea. Those J2F-2A Ducks belonged to VMS-3 and were modified with twin rear machine guns and two additional bomb racks under the lower wings. 

Twenty unarmed J2F-3s were ordered in January 1939 destined for the US Naval Attaches and the Commander of the US Naval Academy, prepared for VIP use. Those "admiral barges" (as they were commonly known) were plush and painted in dark blue and silver. The J2F-3 was powered by a 790 hp Wright R-1820-36 engine, driving a three-bladed constant-speed propeller.

During late 1939 and early 1940, as war was getting closer to the United State's borders, new military outposts were established. Therefore more Ducks were needed to support the extended patrol areas. The J2F was ideal for operating from those improvised outposts, which were usually shallow inlet facilities, or single ramp docking facilities. In September 1939 production of thirty-two J2F-4s began at Grumman. This version was the same as all previous variants, with minor modifications in cockpit instruments and engine operation.

Sources:

1. https://en.wikipedia.org/wiki/Grumman_J2F_Duck

2. Squadron Signal - Aircraft in Action Mini 7 - Grumman JF Duck

Grumman JF Duck

 

The Grumman JF Duck was an American single-engine amphibious biplane manufactured by Grumman during the 1930s decade.

The Duck was designed in 1932, inspired by the designs of previous amphibious aircraft like the Loening OL and was one of the first designs of the, back then, newly created Grumman. 

The prototype, XJF-1, flew for the first time on 24th April 1933, in Farmingdale, Long Island with Paul Hovgard at the controls.

The XJF-1 was a compact single-bay biplane with a crew of two, seated in tandem under an enclosed canopy. It was powered by a single Pratt & Whitney R-1830-62 radial engine and was armed with a single .30 in caliber flexible machine gun placed at the rear, operated by the observer. It could also carry a single 100 lb (45 kg) bomb under each lower wing. In the rear of the float, two passengers could be accommodated side-by-side. This compartment was accessed through a set of folding doors located in the floor of the rear cockpit. The float was faired into the fuselage, like previous Loening models did. The main landind gear retracted into the float, while the non-retractable tailwheel, mounted at the rear of the main float, acted as a water rudder too. It was also equipped with an arresting hook, which was mounted at the rear of the fuselage. 

The XJF-1 was delivered to the US Navy and underwent evaluation at NAS Anacostia, in Washington DC on 4th May 1933. As a result, the vertical tail surfaces were changed because the original triangular ones resulted in some longitudinal instability. The surfaces were redesigned to the broader squarer vertical surfaces found in the production models of the regular JF Duck. The XJF-1's tail was redesigned, redelivered and accepted into service. Unfortunately, the XJF-1 crashed in the James River on 8th March 1934 when operating with VX-1D5, a naval test and development unit, based at NAS Norfolk in Virginia.

The Duck was ordered into production in 1934. The production version differed from the prototype in having a different rudder, fin and its armament deleted (although it still had provision for a defensive machine gun) with a third crew member (a radio operator) was added. The US Navy issued a contract for twenty-seven JF-1 and the first JF-1 entered into service at NAS Norfolk, Virginia in May 1934. The US Marine Corps (USMC) also undertook the type during February 1935. In the US Navy the JF-1 served in VJ-1 (Utility Squadron 1), attached to USS Wright (AV-1) with detachments aboard the main carriers of the time, USS Saratoga (CV-3), USS Lexington (CV-2) and USS Ranger (CV-4) and also aboard USS Heron (AM-10) in the Asiatic Fleet.

It was also assigned at the Navy's main shore bases like Coco Solo in the Panama Canal Zone, Pearl Harbor in Hawaii and the Navy Yard, at Cavite in the Philippines. 

The JF-2 was a development of the JF-1 built in 1934-1935 for the US Coast Guard. The JF-2 were powered by a single Wright R-1820-102 rated at 700 hp. The JF-2 were equipped with a radio direction finder loop antenna placed on the fuselage spine behind the canopy and it lacked arrestor gear. The JF-2 served with the US Coast Guard from land bases in New Jersey, Washington, Florida, North and South Carolina, Mississippi, and California, as well as aboard USCG cutter Taney (WHEC-37), in Honolulu, Hawaii, the USCG icebreaker Spencer (WPG-36) in Cordova, Alaska, where it also served in the Bering Sea Patrol unit. Four JF-2 were transferred to the US Navy. 

The JF-3 was a further development built both for the US Navy and USMC reserve units in 1935. Only five of them were built and were powered by a single 750 hp Wright R-1820-80 engine. Like the JF-2 it also lacked the arrestor hook. A single JF-3 was delivered to each of the major reserve bases at NRAB Brooklyn, in New York, NRAB Seattle in Washington, NRAB Long Beach, California and NRAB Opa-Locka, in Florida. 

The JF Duck also had one foreign customer: Argentina. In 1937 Argentine Government bought eight Grumman model G-20 Ducks directly from Grumman. The G-20 was similar to the JF-2 used by the US Coast Guard. The first Argentine G-20 flew for the first time in December 1936 and by February 1937 they were all delivered. They replaced the outdated Vought O2U-1As in the Escuadrón de Observación Naval (Naval Observation Squadron). They operated from BAN (Base Aérea Naval - Naval Air Base) Comandante Espora, other Argentine Navy's bases like BAN Puerto Belgrano and aboard the cruisers ARA Almirante Brown (C-1) and ARA Veinticinco de Mayo (C-2). They served until 1948. 

Sources:

1. https://en.wikipedia.org/wiki/Grumman_JF_Duck

2. Squadron Signal - Aircraft in Action Mini 7 - Grumman JF Duck

3. https://www.valka.cz/topic/view/160020/Grumman-JF-1-Duck

4. http://wings-aviation.ch/51-Profiles/G/G-Basis-en.htm

5. http://elmuan.blogspot.com/2011/08/1937-grumman-g-15-y-g-20-duck.html (translated)

6. http://www.histarmar.com.ar/Armada%20Argentina/AviacionNaval/REC-AT-GrummanDuck.htm (translated)

Martin B-10

 

The B-10 waged a revolution in bomber design with its all-metal monoplane airframe, enclosed cockpits, rotating gun turrets, retractable landing gear, internal bomb bay and full engine cowlings. With all those features, the bomber marked the standard for the designs to come in the following decades, making the existing designs obsolete and Martin receiving the 1932 Collier Trophy for designing the XB-10.

It began initially as a private venture with the Martin Type 123, by Glenn L. Martin Company in Baltimore, Maryland. It was manned by a crew of four, pilot, co-pilot, nose gunner and fuselage gunner. At first, all four crew compartments were open, but it had a number of design innovations as well.

Innovations included a deep belly for an internal bomb bay and a retractable landing gear. The Type 123 was powered by two 600 hp Wright SR-1820-E Cyclone radial engines and flew for the first time on 16th February 1932. It was delivered to the US Army on 20th March as the XB-907 for testing. After evaluation by the US Army, it was sent back to Martin for redesign and improvement and it was rebuilt as the XB-10.

The XB-10 was later delivered to the US Army and it differed in many ways from the original aircraft. It had full NACA cowlings to decrease drag, while the XB-10 had Townend rings. It also was powered by two 675 hp Wright R-1820-19 engines and had a larger wingspan, together with an enclosed nose turret. When further trials were performed on the XB-10 in June 1932, it achieved a speed of 197 mph (317 km/h) at 6.000 ft (1.830 m) high, quite an impressive performance for the time. 

After the success of the XB-10, some changes were made to the design. The number of crew members was reduced to three and canopies for all of them were added. The US Army ordered an initial batch of 48 of these on 17th January 1933. The first 14 of them were labelled as YB-10 and were delivered to Wright Field, Ohio, from November 1933 onwards and used in the Army Air Corps Mail Operation.

Later, in 1935, the Army ordered an additional 103 aircraft, named as the Martin B-10B, which differed only in minor details from the YB-10. Deliveries began in July 1935 and they served with the 2nd Bomb Group at Langley Field, Virginia, the 9th Bomb Group at Mitchel Field, New York, the 19th Bomb Group at March Field, California, the 6th Composite Group in the Panama Canal Zone and the 4th Composite Group in the Philippines. Some modified YB-10s and B-12 (the remaining aircraft of the original order, which were powered by two Pratt & Whitney R-1690-11 Hornet radial engines) were operated with twin floats for coastal patrol duties.

In February 1936 thirteen B-10Bs belonging to the 49th Bomb Squadron dropped supplies to the residents of Tangier Island, in Virginia and Smith Island, in Maryland as ships couldn't reach due to heavy ice in the Chesapeake Bay and the inhabitants faced starvation after a sever winter storm. 

Although at the time of its creation it was a very advanced design (General Henry H. Arnold referred the bomber as the airpower wonder of its day), rapid advances in bomber design during later 1930s meant that the bomber was completely obsolete by the time the World War 2 began. A modernisation effort was made with the Martin 146, but it was superseeded by the Boeing B-17 and the Douglas B-18. 

Ironically, although by the time the USA entered the war the B-10 was retired from active service long ago, an export model used by the Dutch East Indies escaped to Australia on 7th March 1942 and was taken on strength by the USAAF to serve as an utility aircraft. That was the only Type 139WH-3/Type 166 to serve with the United States Army Air Forces.

Sources:

1. https://en.wikipedia.org/wiki/Martin_B-10

2. http://www.joebaugher.com/usaf_bombers/b10.html

Douglas B-18 Bolo, part one

 

The Douglas B-18 Bolo was an American medium bomber which served with the United States Army Air Corps (USAAC) during the late 1930s and early 1940s. 

In 1934 the USAAC requested a bomber with double payload and range than the Martin B-10 which, was just entering service as USAAC's standard bomber. The next year an evaluation was carried out at Wright Field, Ohio, where Douglas showed their DB-1 design and competed with the Boeing Model 299 (which would eventually be improved into the Boeing B-17 Flying Fortress) and the Martin 146. 

Boeing's candidate was clearly superior, however, as pilots forgot to unlock controls when taking off causing the prototype to crash, it was removed from consideration and its high price per unit ($58.500 vs $99.620 of the Model 299 - $1.105.142 and $1.881.953 adjusted for inflation in the past year) also played a big factor in making the DB-1 as the chosen bomber. Therefore the DB-1 was ordered into mass production in January 1936 as the B-18.

The DB-1 design was basically the same as the DC-2 with many modifications. The wingspan was 4.5ft - 1.4m larger, the fuselage was deeper to better fit bombs and the six-men crew, the wings were fixed in the middle of the cross section instead of the bottom because of the deeper fuselage. It was equipped with three turrets, placed in the nose, ventral and dorsal positions, with this last one being retractable. Each turret was equipped with one Browning 0.3in machine gun. It could also carry a normal payload of 2.000 lb (910 kg) of bombs, however, it could be overloaded up to 4.400 lb (2.000 kg) at maximum. 

Sources:

1. https://en.wikipedia.org/wiki/Douglas_B-18_Bolo

2. https://www.valka.cz/Douglas-B-18-t72780

3. http://www.aviation-history.com/douglas/b18.html

Curtiss XF12C-1/Curtiss XS4C-1/Curtiss XSBC-1

The Curtiss XF12C-1 was one of the designs that ended up being the original Curtiss SBC Helldiver. It was based on a US Navy Bureau of Aeronautics for a two-seat fighter which was ordered on 30th June 1932. It was an all-metal parasol monoplane which featured aft-folding wings (feature which, back then, was new for the US Navy as the aircraft was designed with carrier-storage in mind) with leading-edge slats, trailing-edge flaps and manually-operated retractable main undercarriage members.
The prototype flew for the first time in July 1933 and was initially powered by a Wright R-1510-92 radial engine which delivered 625 hp of power and was armed with two 0.3 in Browning machine guns firing forward and another defensive one at the rear mounted on a flexible mount.
By the time the XF12C-1 was tested by the US Navy, in October 1933, the R-150-92 engine was already being rejected for being too unsatisfactory. After testing, the aircraft was discarded for the fighter role, and on 7th December 1933 the only tested prototype was redesigned in the scout category as the XS4C-1 and re-engined with a 700 hp Wright 1820-80 radial engine, which drove a two-bladed propeller. In this new scouting role, it had to carry equipment for a 500 pound (227 kg) bomb, so it was re-labelled in January 1934 as XSBC-1.
In early 1934 flight-testing, specially centred in dive-bombing manoeuvres began and, on 14th June 1934 the aircraft crashed, supposedly due to a wing failure in Lancaster, New York, close to one of Curtiss' plants, during one of the tests and was destroyed.

Sources:
1. https://en.wikipedia.org/wiki/Curtiss_SBC_Helldiver
2. http://www.aviastar.org/air/usa/curtiss_f12c.php
3. https://www.valka.cz/Curtiss-XF12C-1-t127850
4. Signal Squadron - Aircraft In action 151 - SBC Helldiver in Action

Vought OS2U Kingfisher, part five

The Vought OS2U Kingfisher was designed by Vought's main designer Rex B. Beisel as he was tasked with designing an observation monoplane aircraft for the US Navy that could commit many tasks like directing Battleship fire. By replacing the standard Vought O2U Corsair biplane, Beisel incorporated production innovations as it was the first production type to be assembled with spot welding, a process developed jointly by both Vought and Naval Aircraft Factory in order to create a smooth fuselage resistant to buckling and with less drag. Biesel also introduced high-lift devices, spoilers and deflector flaps and drooping aillerons located on the trailing edge of the of the wing. This arrangement was unique to the Kingfisher, and were deployed to increase the camber of the wing creating, therefore, additional lift.
It was armed with a single 0.30 in Browning machine gun, with the receiver mounted low in the right front cockpit, which fired between cylinder heads, with another one, mounted on a flexible Scarff ring, for the radio operator/gunner. It could also carry two 100 lb bombs or two 325 lb depth charges. Additionally, the Kingfisher (as it was designated), was used as a trainer in both landplane and seaplane variants.
The prototype flew for the first time in 1938 and was powered by a 450 hp Pratt & Whitney R-985-4 Wasp Junior radial engine. The first variants, called OS2U-1, were powered by the Pratt & Whitney R-985-48 air-cooled radial engine which yielded 450 hp of power. The second variant, was powered by a slightly improved variant of that same engine, P&W R-985-50 and was named OS2U-2 , the third variant, OS2U-3 was powered by a P&W R-985-AN2 and some of them, manufactured by the Naval Aircraft Factory, received the denomination of OS2N-1. All of them yielding 450 hp of power. A fourth variant, OS2U-4 was in the works, with narrow-chord and high-aspect ratio wings, fitted also with full-span flaps, however it wasn't developed.
A total of 1519 machines were manufactured of every variant at Vought-Sikorsky Aircraft Division's factory in Stratford, Connecticut and the Naval Aircraft Factory in Philadelphia.

Sources:
1. https://en.wikipedia.org/wiki/Vought_OS2U_Kingfisher
2. Signal Squadron - Aircraft In action 119 - OS2U Kingfisher in Action
3. https://www.valka.cz/topic/view/141347/Vought-OS2U-1-Kingfisher
4. https://www.valka.cz//topic/view/1179

Douglas DC-1

The Douglas DC-1 was the first model of the famous American DC (which stands for Douglas Commercial) commercial transport aircraft series. Only one aircraft was produced, but it served as the basis for the DC-2 and DC-3.
Its development dates back to 1931 after a TWA's (Trans World Airlines) Fokker F.10 crashed due to the failure of a wing caused by the water that had seeped between the layers of the wood laminate and dissolved the glue that held the layers together. After the accident, the Aeronautics Branch of the US Department of Commerce placed strict restrictions on the use of wooden wings on passenger airliners. Boeing answered with a new model, the Boeing 247 which was a twin-engined all-metal monoplane with a retractable undercarriage, but their production capacity was reserved to meet the needs of United Airlines, part of United Aircraft and Transport Corporation which also owned Boeing. Therefore TWA needed a similar aircraft to compete with the Boeing 247 and they asked five manufacturers to bid for construction of a three-engined, 12-seat aircraft of all-metal production with a range of 1080 milles (1740 km) at 150mph (242 km/h). The most difficult specification was that the aircraft had to be able to safely take-off from any airport on TWA's main routes with one engine non-functioning. The most difficult one to operate was Albuquerque's airport which is at high altittude and with sever summer temperatures.
Donald Douglas, president of Douglas Aircraft Company was initially reluctant to take part in the contest as he doubted that there was enough market for 100 aircraft, which was the number of sales needed to cover development costs. However, he submitted a design consisting on an all-metal, low-wing, twin-engined aircraft with capacity for 12 passengers, a crew of two and a flight attendant. The specifications exceeded the needs of the TWA even with only two engines, mainly through the use of controllable pitch propellers. It was also insulated against noise, heated and fully capable of flying and making a controlled taking-off on just one engine.
As stated by Donald Douglas, the DC-1 costed $325.000 (That's $5,956,917.88 adjusted for inflation) of the time to design and build.
Only one aircraft was produced and flew for the first time on 1st July 1933 at the hands of Carl Cover. It received the designation of DC-1 (standing for 'Douglas Commercial-1'). It was tested for half-year and performed over 200 test flights proving its superiority over other airliners of the time like the Ford Trimotor or Fokker Trimotor. It was flown accross the USA from New York to Los Angeles, on 19th February 1934 setting a new record of 13 hours and 5 minutes.
Back on 15th September 1933, TWA accepted the aircraft with some modifications like an increased passenger capacity from 12 to 14 and adding more powerful engines. They also ordered a production of 20 of them which, at its developed version would be known as the Douglas DC-2.
The DC-1 never entered active service with TWA but was used for promotion purposes. It was sold in May 1938 to Lord Forbes in the United Kingdom, who operated it for a few months as his personal aircraft and was sold in October to the French Société Française de Transports Aériens which sold it just weeks later, in November 1938 to the Spanish Republicans.
It was assigned to the LAPE (Lineas Aéreas Postales Españolas - Spanish Postal Airlines) where it saw at least two camouflage schemes (as shown below) and was notorious for having transported the Spanish Republican Cabinet to the exile on 6th March 1939 from Valencia to Toulouse, in France.
It was given back to the Francoist authorities after the end of the Spanish Civil War and it was assigned to Tráfico Aéreo Español (Spanish Air Traffic - the most inmediate predecessor of Iberia, Spanish national airline) which re-registered it and named it as "Manuel Negrón". It was lost in December 1940 when after having taken-off from the airport of Malaga, it crashed shortly after for unknown reasons and it was scrapped.

Sources:
1. https://en.wikipedia.org/wiki/Douglas_DC-1
2. https://es.wikipedia.org/wiki/Douglas_DC-1 (translated)
3. https://aeropinakes.com/wordpress/1938/11/13/douglas-dc-1-de-lape-ejemplar-unico/ (translated) 
4. http://jaon.es/dc1/index.htm (translated) 

Boeing P-26

The Boeing Company funded the project to produce the Boeing Model 248 in September 1931, with the US Army Air Corps supplying the engines and instruments. The design included an open cockpit, fixed landing gear and externally braced wings and it was the last of such design procured by the USAAC as a fighter aircraft. The original Model 248 had a very high landing speed which caused many accidents, so in order to remedy that, flaps were fitted to reduce landing speed. The USAAC ordered three prototypes, under the name of Boeing XP-936 with the first flight taking place on 20th March 1932.
The prototype was still hard to land and sometimes, due to its short nose, it rolled onto its back and would flip forward, injuring, or even killing, the pilot. The prototype's unarmed headrest offered virtually no protection in such cases, so the production model, called Model 266 (Boeing P-26A) had a taller armoured headrest installed.
The P-26A version was powered by a single Pratt & Whitney R-1340-27 "Wasp" with a power of 600hp while subsequent versions, the P-26B and C were powered by the R-1340-33 fuel-injected engines. The C version had modified and optimized fuel systems and all of them were armed with two 0.30in (7.92mm) M1919 Browning machine guns or one 0.30in and one 0.50in (12.7mm) calibre machine guns and could carry up to 90Kg (100lb) of bombs.
Back in the early 1930s it was the fastest American fighter aircraft to serve with the USAAC. However, as the aircraft technology was developing very quick, it soon became obsolete with wire-braced wings, fixed landing gear and open cockpit. For comparison purposes, the Dewoitine D.500 flew for the first time the same year as the P-26 and the Soviet Polikarpov I-16 was already flying with retractable landing gear by 1934, just two after the P-26. By 1935, just two year after the P-26 was designed, the Curtiss P-36, the Messerschmitt Bf.109 and the Hawker Hurricane, were all flying with enclosed cockpits, retractable landing gear and cantilever wings. However, as the P-26 was easy to flight, it remained in service with the USAAC until the United States entered the World War II.
It was delivered to the USAAC's Pursuit Squadrons in December 1933 with the last production aircrafts rolling out of the factory in 1936, under the designation of P-26C. Twenty-two squadrons flew the P-26, with peak service being six squadrons in 1936. They were the frontline fighter of the USAAC until 1938 when the Curtiss P-36 and the Seversky P-35 began to replace the P-26. Twenty of them were lost in accidents between 1934 and 1941, but only five before 1940.
They were also assigned to overseas deployment to supplement the Seversky P-35 at Wheeler Field, in Hawaii between 1938 and 1940 and, while some of them remained there as trainers, others were sent to Albrook Field, in the Panama Canal Zone, were nine of them were active in December 1941. They also served with the 3rd Pursuit Squadron of the 4th Composite Group, based in the Philippines and they were sold between 1937 and 1941 to the Philippne Army Air Corps.

Sources:
1. https://en.wikipedia.org/wiki/Boeing_P-26_Peashooter
2. Salamander Books - The Complete Book of Fighters.

Curtiss SOC Seagull, part one

The Curtiss SOC Seagull was an American single-engined scout observation aircraft, which was designed by Alexander Solla when he was working for the Curtiss-Wright company for the United States Navy. It served on board of Battleships and Cruisers in a seaplane configuration, being launched from catapults and recovered from sea landings and also by the United States Marine Corps which used them, limitedly, in the scout role, specially in the years previous to America's entry into World War II.
The wings could be folded back to be storaged aboard the ship and floaters could be replaced by fixed landing-gear to make it operate from shore bases or carriers.
A total of 285 SOC aircraft were manufactured, from every variant from SOC-1 to SOC-4 with the production beginning in 1935 and the SOC-3 being the basis for the Naval Aircraft Factory SON-1 variant of which 64 of them were delivered in 1940.
The prototype flew for the first time in 1934 and every versions were powered by a single Pratt & Whitney R-1340-18 nine-cylinder air-cooled radial engine which yielded a power of 550hp. It had a crew of two, and was armed with one fixed forward-firing 0.3in (7.62mm) Browning M2 AN plus one defensive rear-firing 0.3in Browning M2 AN. It could also carry a payload of 650lb (295Kg) of bombs carried under lower wings.
It was ordered for production by the United States Navy in 1933 and entered service in 1935. The first production order was of 135 SOC-1 models, followed by 40 SOC-2 variants with fixed landing gear for landing operations both carriers and shore bases. A third variant known as the SOC-3 was built by the Naval Aircraft Factory, as we told before and received oficial denomination of SON-1.

Sources:
1. https://en.wikipedia.org/wiki/Curtiss_SOC_Seagull
2. https://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=832

Bell YFM-1 Airacuda

Materializing many innovative features and designed by Robert J. Woods, the Airacuda was a five-seat long-range bomber destroyer. It was powered by two engines in a pusher configuration and it accommodated two gunners in forward extensions of the engine nacelles. Those crew members were provided with wing crawlways in order to reach the main fuselage in the event that it was needed to evacuate the nacelle gun positions.
The first prototype XFM-1 was powered by two 1150hp Allison V-1710-13 12-Cylinder liquid-cooled engines which drove three-blade propellers via 64-in (1.62m) extension shafts and flew for the first time on 1st September 1937.
Twelve further evaluation models were ordered, nine as YFM-1 and other three YFM-1As which was different just in having tricycle undercarriage. The engines kept being two 1150hp Allison V-1710-23s, but three of them were fitted with the V-1710-41 of 1090hp as YFM-1Bs. The 12 YFMs were delivered to the United States Army Air Corps between February and October 1940 and they were armed with one 37mm T-9 cannon in each gun nacelle with 110 rounds each, plus one 0.3in (7.62mm) M2 machine gun with 500 rounds in each of the retractable dorsal turret and ventral tunnel positions and one 0.5in (12.7mm) M2 gun firing from each of the port and starboard beam positions. Twenty 30lb (13.6Kg) bombs could be fitted internally.
During flight testing performed by Bell, many problems and flaw were encountered with two of them being lost to accidents and most of them being damaged. The most accident occurred to an YFM-1A on a flight between Chanute Field, Illinois and Keesler Field, Mississippi when a broken oil line sparked a fire due to some serious fuselage vibration encountered during the flight. As there wasn't any way of extinguishing the fire, both pilot and crew chief agreed to bail out. The pilot was killed as his parachute didn't open. That was the only fatality occurred during the testing of the Airacudas.
In spite of all those problems, a full operation Airacuda squadron was assembled and operated from 1938 to 1940. Funds were appropriatted but never released for the purchase of two further groups of Airacudas. However, as the continued problems persisted, the aircraft received the reputation of "hangar queens". Near the end of the aicraft's operational life they were flown mainly for photo oportunities and always accompanied by a chase plane for security purposes. It was decided eventually to disperse the aircraft through various airfields to give pilots the chance to add the unusual aircraft to their log books, so they were sent to Langley Field, Virginia, Maxwell Field, Alabama, Hamilton Field, California and Wright Field, in Dayton, Ohio. One of them was displayed at the 1940 New York World Fair finished with the colours of the 27th Pursuit Squadron but during this time the aicraft saw limited flight time as pilots weren't interested in flying the unusual aircraft.
Many plans were made to modify them to make them operational, including the modification of the airframe and adding more powerful engines but all of them were rejected. In early 1942 despite the danger of enemy attacks against American bombers, the Airacuda was rejected.

Sources:
1. Salamander Books - The Complete Book of Fighters
2. https://en.wikipedia.org/wiki/Bell_YFM-1_Airacuda

Berliner-Joyce P-16

After the Berliner Aircraft Company was adquired by the newly established Berliner-Joyce Aircraft Corporation in February 1929 with the aim of developing a monoplane but, they got involved in the development of a two-seater biplane for the United States Army Air Corps.
The prototype, named XP-16, flew for the first time in October 1929. It featured an all-metal structure with a fabric covering. It was a single-bay biplane of unequal span and the wings forward-staggered. Lower wing was smaller that the upper one that was mounted on the base of the fuselage in a sesquiplane fashion and, unusually, of the reverse-gullwing type. An observer/gunner post was located just behind the pilot armed with 0.30in Browning machine gun mounted on an scarff ring. It was powered by a 600hp (447Kw) Curtiss V-1570 Conqueror supercharged V-12 inline engine.
It was evaluated by the USAAC and two contracts were awarded for a total of 25 pre-production aircrafts named YP-16 with the main difference being that it was powered by a non supercharged version of the Conqueror engine and that it drove a two-bladed propeller instead of a three-bladed one.
During 1931 the USAAC ordered the YP-16, the pre-production version, which was the last biplane to enter service with the USAAC. Furthermore, the P-16 was the only two-seat biplane fighter to be produced for the army after 1918. It was delivered in 1932 to the 94th Pursuit Squadron and, as most of them were of the YP-16 type and weren't powered by the supercharged version of the engine, performance at altittude was greatly reduced, although it had better endurance than contemporary single-seat fighters. Visibility was poor in spite of the gull-wing and due to that it was prone to nose-overs when landing.
All of them were withdrawn from active service in 1934, although some of them remained in second line duties until 1940.

Sources:
1. https://en.wikipedia.org/wiki/Berliner-Joyce_P-16
2. Salamander Books - The Complete Book of Fighters